CODEWITHSUNDEEP
pythonopencvrtspframe-rate
Alfonso Ponce
Alfonso Ponce

Reputation: 1

How to reduce the number of frames processed in a video feed using OpenCV and Python?

I got a video stream using RTSP protocol that I then send to my Python code using the OpenCV Video.Capture function. I just want to get 1 or 2 frames per second from that feed, process them and show the results of each one of them. Basically the output that I imagine would be a very low frame rate of the original feed with the processing I need. My question is, how do I only get a certain amount of frames to process and not all of them? Thank you!

Upvotes: 0

Views: 2140

Answers (1)

Ibrahim Animashaun
Ibrahim Animashaun

Reputation: 11

You can use the function below to save and write x number of frames per second. The function takes 2 arguments - the video path and the number of frames you want to save per second. frames_per_second has a default value of 1 i.e prints a frame every second. You can change this parameter to increase or decrease number of frames saved per second. If you want to save less than a frame every second, you can input a value between 0 and 1 for frames_per_second e.g. 0.5 will print a frame every 2 seconds and 0.25 will print a frame every 4 seconds. And if you want all frames saved enter a value of -1 for frames_per_second.

import cv2
import math
import os



def video_to_images(video_path, frames_per_second=1):
    cam = cv2.VideoCapture(video_path)
    frame_list = []
    frame_rate = cam.get(cv2.CAP_PROP_FPS) #video frame rate



    # frame
    current_frame = 0
    
    # create directory if it does not exist
    images_path = f'./data/images' 
    if not os.path.exists(images_path):
        os.makedirs(images_path)

    if frames_per_second > frame_rate or frames_per_second == -1:
        frames_per_second = frame_rate
    
    while(True):
        
        # reading from frame
        ret,frame = cam.read()
    
        if ret:

            # if video is still left continue creating images
            file_name = f'{images_path}/frame' + str(current_frame) + '.jpg'
            print ('Creating...' + file_name)
            # print('frame rate', frame_rate)



            if current_frame % (math.floor(frame_rate/frames_per_second)) == 0:

                # adding frame to list
                frame_list.append(frame)

                # writing selected frames to images_path
                cv2.imwrite(file_name, frame)
    
    
            # increasing counter so that it will
            # show how many frames are created
            current_frame += 1
        else:
            break
    
    # Release all space and windows once done
    cam.release()
    cv2.destroyAllWindows()

    return frame_list

Upvotes: 1

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